Modeling and Crystal Plasticity Analysis of Multiple Slip Deformation in the Microstructure of Particle Dispersed Alloy and Its Macroscopic Strain Hardening Characteristics

摘要

Multiple slip deformation in dispersion hardening steels are numerically analyzed by a crystal plasticity finite element technique and macroscopic strain hardening characteristics are discussed. The critical resolved shear stress (CRSS) for slip system is given by the extended expression of the Bailey-Hirsch type model which include contributions from lattice friction, Taylor hardening and also the Orowan stress to give a size effect from microstructure. Strain hardening of slip systems are estimated by the density of statistically stored dislocations (SSDs) through the Taylor term. Increment of the SSD density is evaluated by slip strain and the dislocation mean free path. Models for the CRSS and dislocation mean free path for the primary and secondary slip systems are discussed. Analysis results show that macroscopic yield stress agrees well with experimental one but strain hardening ratio is overestimated when the CRSS and dislocation mean free paths for secondary systems are given the same characteristics of scale dependency to that for the primary one. Some new models for the CRSS and mean free path for secondary systems are studied and analysis results with these models show to agree well not only for the yield stress but also for the strain hardening behavior.